Fiber-to-the-node

From Hill2dot0

Fiber-to-the-node (FTTN) is an approach to delivering multimedia services to the home at a much lower cost than fiber-to-the-premises (FTTP). FTTN uses fiber to a distribution node and then employs DSL over the existing local loop for the final connection to the customer. The node is usually placed 1-3000 feet from the customer. Shortening the local loop allows the DSL to use much higher frequencies than conventional DSL technologies. ADSL2+ is currently the favored technology, with VDSL2 expected to become the technology of choice in the future. ADSL2+ offers a connection up to 25 Mbps; VSDL2 will offer 100 Mbps.

One of the challenges with FTTN is the delivery of video services. FTTN has a POTS connection that uses the low frequencies on the local loop and a high-speed data channel. The data channel is used to deliver Internet access and video services. This model requires the video services to receive priority over Internet data. The IP television (IPTV) technology is still being developed. Some have compared the FTTN and IPTV deployment to building an aircraft while flying. So far, there has been limited deployment of FTTN; however, 2007 will see a significant increase in deployment.

FTTN Architecture

FTTN Architecture

The visual depicts the FTTN architecture. In this network the services are delivered to a distribution point (node) using optical fiber; from this point the connection to the customer uses the existing local loop (twisted pair). VDSL2 has been developed for this scenario.

In this architecture there is no option to deliver TV in the traditional mode, so a new approach is required. Carriers are not choosing IPTV to deliver television services.

FTTN can be deployed more rapidly than FTTP at lower cost. For companies with a high percentage of customers served by buried loops it is a cost-effective approach to delivering new services. The downside to this approach is there is no room for future expansion as the copper loop limits the available bandwidth. Customers must consider whether100 Mbps is enough to meet their future needs.

FTTN Loop Options

In FTTN systems, the choice of loop options is based on distance and speed. FTTN and FTTP can be deployed by the same provider if a compatible backbone system is used (e.g., PON). For the last mile or thousands of feet, there are several choices.

Fiber can be fed to a building for dispersal to the offices or tenants.

ADSL has been the mainstay for DSL service for the better part of a decade. An advanced version of ADSL, ADSL2+ offers up to 25 Mbps over short distances (.5 km). The speeds drop off as the distances increase.

VDSL was defined as the broadband service vehicle during the early deployment of ADSL. Today VDSL2 offers speeds up to 100 Mbps over distances of a half of kilometer.

An FTTN deployment can use a mixture of ADSL2+ and VDSL2 as well as FTTP. The choice depends on the speeds desired, the distances involved, and the costs of the systems. Greenfield deployments might use FTTP, while existing neighborhoods could use either DSL version.